Textile processing



1970 J. w. CASE ETAL TEXTILE PROCESSING Filed Sept. 13, 1967 2 Sheets-Sheet 1 p O E 5 i I35 l4 5 firm-mazes United States Patent US. Cl. 8-142 12 Claims ABSTRACT OF THE DISCLOSURE This invention relates to the processing of textile materials and particularly to an improved treatment to remove volatile organic liquids from textile matenals.

Volatile organic liquids are used extensively in industry for the treatment of textile materials. For example textile fibres are often given a treatment (commonly termed scouring) with halogenated hydrocarbon solvents such as trichloroethylene and perchloroethylene to remove grease, Wax, dirt and other extraneous matter from the surface of the fibres; dyestuffs and coating compositions are often applied to textile materials from solution in organic solvents; and organic solvents are used to dry-clean textiles. In the majority of cases the textile material emerging from a treatment with an organic liquid contains the organic liquid, and it is usually necessary to remove the liquid prior to further treatment or storage of the textile material, and to recover the liquid for re-use.

It is known that volatile organic liquids or suitable boiling point can be removed from textile materials by [flashing-oil the solvent, for example by contacting the textile material with hot Water or steam to volatilise the solvent, these techniques having the advantage that they can be carried out as continuous processes. In these known processes employing steam the textile material, after passage through steam, is passed directly through a water seal to prevent steam and solvent vapour from the treatment vessel escaping to the atmosphere and also, where the treatment follows the scouring of grey goods, to facilitate removal of sizes. In both the hot water and steam flash-off techniques, therefore, the resulting textile material is obtained in the Wet state and, depending upon the subsequent treatment, may require to be dried in a separate operation.

It is an object of the present invention to provide a rapid continuous treatment'for removing volatile organic liquids from textile materials which results directly in a substantially dry textile material and which obviates the disadvantages of air-drying treatments, for example, long contact times and low efficiency of solvent recovery.

According to the present invention we provide a process for removing a volatile organic liquid from a textile material which comprises contacting the textile material containing the volatile organic liquid with steam in a treatment vessel to vaporize said organic liquid, and withdrawing the textile material from the treatment vessel directly into the atmosphere.

It has been found, surprisingly, that the textile material can be treated with steam and yet it emerges from the treatment vessel substantially free from moisture; in fact the moisture content of the treated textile materials in the case where the treatment follows a treatment with boiling organic liquid (as in scouring) can be lower than the natural moisture content of the materials.

The treatment of the present invention is particularly suitable for carrying out as a continuous process and can advantageously follow directly a continuous solvent treatment. For example in a scouring process the textile material can be passed continuously through an appropriate boiling chlorinated hydrocarbon solvent, and then the solvent-laden textile material can be passed directly (if necessary after expression between rollers to remove excess solvent) into a vessel where it is contacted with steam, and then directly into the atmosphere. The scouring liquor, which will normally be used at an elevated temperature of up to its boiling point can advantageously be incorporated in a zone of the same vessel in which the steam treatment is effected so that the textile material is scoured, freed from solvent and dried in a single pass through the vessel. It will be evident that the steam treatment can follow any continuous process in which a textile material is subjected to a volatile liquid which becomes entrained in the textile material.

Preferably the steam used in the treatment is caused to flow counter to the direction of movement of the textile material. A suitable vessel for carrying out the treatment has an inverted U-shaped section into one end of which there is fed the textile material and into which there is introduced steam in such a manner that the steam is caused to flow through the vessel towards the end into which the textile material is fed. A condenser is advantageously provided in the leg of the vessel into which the textile material is fed so that the mixture of steam and solvent vapour formed within the vessel due to volatilization of the solvent by the steam passes through the vessel and into the condenser, where the vapours (i.e. steam and solvent) are condensed. The organic liquid in the condensate can be recovered by conventional methods, for example using a water separator, for further use. Slight reduction in pressure within the condenser assists withdrawal of the solvent vapour and steam from the treatment vessel and thus assists flow of steam through the vessel. The condenser is preferably vented to the atmosphere to allow proper balance of pressure in the system.

It is to be understood that the treatment vessel need not necessarily be of inverted 'U-section, and can in fact have a variety of shapes. It is considered desirable, however, that the exit from the vessel is constructed so that the textile material is Withdrawn through a duct through which fresh live steam flows counter to the direction of movement of the textile material. This is considered to be advantageous since loss of solvent vapour .to the atmosphere is thereby prevented. The reaction vessel can be constructed so that the textile material passes from the steam treatment chamber through a narrow opening into a second chamber filled with steam, and from this second chamber through a narrow opening into the atmosphere. The continuous introduction of steam into the second chamber forms a steam-trap which ensures that the textile material leaves the treatment chamber through a duct in which it is contacted with counter current steam and which, therefore, ensures that the mixture of steam and solvent-vapour formed Within the treatment chamber cannot escape freely into the atmosphere. The steam trap further ensures a slight escape of pure steam into the atmosphere through the outlet for the textile material and this is advantageous in that entry of air into the treatment vessel through the exit duct is preprevented. Air entering the treatment vessel results in loss of solvent vapour via the air-vent in the condenser and solvent recovery is consequently impaired. The textile material can be withdrawn through a suitable mechani cal seal, for example an inflatable seal comprising pneumatic bags coated with polytetrafluoroethylene.

Condensation of the steam and the solvent vapours within the treatment vessel occurs due to cooling of the vapour mixture on contact with the walls of the vessel, and drip-trays or other deflection :means can be provided to prevent the resulting liquids from dripping onto the textile material. Condensation can be reduced by heating and/or lagging the walls of the treatment vessel.

The textile material to be treated can be in a variety of forms, for example it can be in the form of a web or fleece of individual fibres or filaments, or in the form of yarns or woven or non-woven fabrics, including needled or felted webs, carpets, knitted goods and the like. If the textile material has insufficient strength to be selfsupporting, it can be conveyed through the treatment Vessel on a suitable transport system. The textile material can be of any natural fibres such as cotton or wool, or manmade fibres such as polyester and polyamide fibres, or mixtures thereof.

The organic liquid which is to be removed from the textile material can be any organic liquid which is volatilised by contact with steam. Preferably the organic liquid does not have a boiling point in excess of 125 C., and examples of suitable liquids are halogenated aliphatic hydrocarbon solvents such as methylene chloride, 1:1:1- trichloroethane, trichloroethylene, perchloroethylene, and trichlorotrifiuoroethane. However, the invention is not limited to the removal of halogenated hydrocarbons from textile materials, and alternative organic solvents may be used if desired.

The steam used in the treatment is preferably, but need not necessarily be, superheated steam and can be introduced at one or more points in the treatment vessel. The flow of steam into the treatment vessel can be controlled automatically by means of valves operated by thermostats positioned within the vessel, so as to maintain the temperature inside the vessel within set limits, for example 90 C. to 100 C. in the case where trichloroethylene is used as the solvent. Where these temperatures are used, the trichloroethylene for the scouring treatment can conveniently be used at a temperature of about 60 C., but it can be boiling if desired.

As stated hereinbefore, the textile material containing the volatile organic liquid need not be heated prior to the treatment with steam, and vice versa if the textile material is at an elevated temperature due to treatment with hot organic liquid, then it need not be cooled prior to the treatment. The textile material can conveniently be passed continuously through the treatment vessel within which it is preferably in contact with the steam for a period of from two seconds to five minutes depending upon the form of the textile material. For open width fabrics, steam treatment times from five seconds to fifteen seconds are usually sufficient, but for blankets in rope form periods up to five minutes may be required.

The invention is illustrated by way of example only with reference to the accompanying drawings, in which FIG. 1 shows schematically a suitable treatment vessel, FIG. 2 shows an alternative construction of the outlet from the treatment vessel shown in FIG. 1, and FIGS. 3 and 4 show alternative constructions of the treatment vessel. All the figures represent vertical sections.

Referring to FIG. 1 the treatment vessel comprises a steam chamber 1 of inverted U-shaped cross-section having one leg 2 of greater width than the other leg 3. The lower end of the leg 2 contains an organic solvent 4 (only a portion of the lower end of the leg 2 is shown in the drawing). Rollers 5, one or more of which may be driven, are provided to enable passage of a woven fabric 13 through the treatment vessel. There are also provided rollers 6 in the form of a mangle for expression of excess solvent from the fabric, and steam jets 7 and 8 for introducing steam into the chamber. A duct 9 connects the leg 2 to a condenser 10 which has an airvent 11. A deflection tray 12 is provided to prevent condensed steam and vapours from dripping on to the fabric from the roof of the steam chamber.

In using the treatment vessel for removal of liquid solvent from a woven fabric, the fabric 13 is introduced into the steam chamber 1 through the solvent 4 (in which the fabric can be scoured, for example) and the rollers 6 and is withdrawn through the outletduct 14 in the leg 3. During the passage of the fabric steam is introduced continuously through the jets 7 and 8, the major proportion of the steam entering through jet 7. The steam fiows from the leg 3 and the jets 7 through the steam chamber and into the condenser 10 via the duct 9, and in so doing causes volatilization of the solvent from the fabric. The solvent vapour becomes entrained in the steam and passes with the steam into the condenser 10 wherein the steam and the vapour are condensed. The condensate is removed to a separate vessel (not shown) where the solvent is separated for re-use. A high percentage (eg of the solvent in the fabric is volatilized in the leg 2 of the steam chamber 1, and volatilization of the solvent is substantially completed by the time the fabric passes the steam jets 7. The minor proportion of steam introduced through jets 8 serves to remove entrained solvent vapour from the fabric in the leg 3 and to prevent escape of solvent vapour into the atmosphere via the duct 14.

The steam introduced through jets 8 also serves to ensure a slight leakage of pure steam through the duct 14 into the atmosphere.

It will be readily understood that slight variations may be made to the treatment vessel shown in FIG. 1, for example the mangle, rollers 6 can be excluded in certain uses of the vessel, and one or more of the rollers 5 may be associated with another roller to provide a light nip. Also, a metal seal or a seal of metal with a covering of rubber or other soft material may be provided at the outlet duct 14 of the leg 3 to minimize steam losses to the atmosphere. The walls of the vessel may be lagged and/ or provided with heating means to minimize condensation within the steam chamber.

An alternative construction for the exit leg 3 of the steam chamber is illustrated in FIG. 2. In this construction a second steam chamber 15 is provided, this chamber 15 being in communication with steam chamber 1 by an outlet duct 16 formed in the leg 3 by internal bafiles 17 which are welded in the leg 3. An outlet duct 18 formed by welding suitable bafiles 19 in the leg 3 is provided at the lower end of the steam chamber 15. Steam jets 20 ensure flow of steam from the steam chamber 15 to the steam chamber 1 to prevent escape of solvent vapour to, and entry of air into the steam chamber 1 from, the atmosphere. The chamber 15 thus acts as a steam trap. The baffles 17 and 19 need not be welded into the leg 3 and can be provided in any manner, for example the leg 3 can itself be suitably shaped, and if desired seals can be provided at either or both of the ducts 16 and 18.

FIGS. 3 and 4 show alternative constructions of the treatment vessel and for simplicity the reference numerals used in these figures are the same as those used in FIGS. 1 and 2.

The invention is further illustrated by the following example which describes the treatment of a woven cotton fabric in the treatment vessel shown in FIG. 1.

EXAMPLE A woven cotton fabric 13 of width 54 inches and weight 4 oz./sq. yard was passed through the treatment vessel shown in FIG. 1. The solvent 4 was trichloroethylene and the fabric, after expression between the rollers 6 contained about by weight based on the fabric of the solvent.

Superheated steam was introduced continuously through the steam jets 7 and 8 and flowed substantially counter to the direction of movement of the fabric. The fabric was passed at a rate of 8 yards/min. and was in the steam chamber for a period of 12 seconds, before being withdrawn directly into the atmosphere. The fabric was found to contain less than 0.1% of its weight of trichloroethylene and had a moisture content of about 1% (compared with the normal moisture regain for similar cotton fabrics of 7% to 8%).

The above procedure was repeated except that the fabric was replaced by a woven cotton fabric of width 54 inches and weight 8 oz./sq. yard. The treated fabric was also found to contain less than 0.1% of trichloroethylene and had a moisture content of about 1%.

What we claim is:

1. In a process for treating a textile material with a volatile organic liquid which is a halogenated hydrocarbon dry-cleaning solvent by wetting the textile with the volatile organic liquid, subsequently removing the organic liquid by vaporizing the organic liquid with steam while passing the organic liquid wetted textile through a treatment vessel, then through a water seal and then into the atmosphere, the improvement comprising removing the volatile organic liquid from the textile material with steam flowing in a direction counter to the textile material in the treatment vessel and withdrawing the textile material from the treatment vessel directly into the atmosphere.

2. A process as claimed in claim 1 which is carried out as a continuous process.

3. A process as claimed in claim 1 wherein steam is introduced into the treatment vessel at a point adjacent to the outlet for the textile material.

4. A process as claimed in claim 1 wherein superheated steam is used.

5. A process as claimed in claim 1 wherein steam is introduced into the treatment vessel at a rate such that the temperature within the vessel is maintained in the range 90 C. to 100 C.

6. A process as claimed in claim 1 wherein the mixture of steam and vapour of the organic liquid formed within the treatment vessel is condensed to recover the organic liquid.

7. A process as claimed in claim 1 wherein the textile material is passed into the treatment vessel directly from a vessel in which it is subjected to a continuous treatment with the volatile organic liquid.

8. A process as claimed in claim 1 wherein the volatile organic liquid has a boiling; point of not greater than C.

9. A process as claimed in claim 1 wherein the volatile organic liquid is trichloroethylene.

10. A process as claimed in claim 1 wherein the volatile organic liquid is perchloroethylene.

11. A process as claimed in claim 3 wherein the pure steam is caused to escape from the treatment vessel through the outlet for the textile material.

12. A process as claimed in claim 6 wherein the steam is passed through the treatment vessel counter to the textile material and the resulting mixture of steam and the vapour of the organic liquid is; passed to a condenser positioned adjacent the inlet for the textile material.

References Cited UNITED STATES PATENTS 3,106,460 10/ 1963 Topham et a1 8-142 XR 3,123,494 3/1964 Charreau 8142 XR MAYER WEINBLATT, Primary Examiner US. Cl. XE, 34 2.3

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,5 ,5 Dated November 97 Inventor(s) John William Case and John Shaw It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, in the heading, after "Filed Sept. 13, 1967, Ser. No. 668,992" insert --Cla.ims priority, application Great mite-1n, Sept. 23, 42,620/66-.

6M) Atteat:

Edward M. Fletcher, It.

fi-omissionar of Patents wmmr. JR. 

